1921] NATUR.\.L SCIENCES OF PHILADELPHIA. 151 



There are, of course, several objections against this statement. 

 For instance, after jumping, the animalcule seems not to have 

 suffered any change in the state of the pharyngeal "cage." But 

 that objection is not strong, in fact is perhaps in favor of the 

 theory. After one jump, even two or three, the "cage" looks 

 complete, but it would be practically impossible to detect the 

 loss of one or two granules, and one of them, indeed, on account 

 of its large size compared to one of the small superficial trichocysts, 

 would suffice to cause a leap, its sudden transformation into a con- 

 siderable mass of some light matter (fine granules, liquid material, 

 slime, or gas?), which would find its way out through the nar- 

 rowed aperture of the fossa, would certainly cause a violent reaction 

 backward. But though after two or three of these leaps the pharyn- 

 geal cage is still intact, it appears, indeed, very different when fre- 

 quent and violent leaps have rapidly succeeded one another ; the cage, 

 then, is seen to be disrupted, the granules, much diminished in 

 number, are scattered in a shapeless mass; sometimes a very few 

 persist, perhaps immature ones, which did not explode. Sometimes, 

 when the animalcule is subjected to the greatest possible excitation, 

 as when a chemical reagent, for instance, comes into play, the jumps 

 rapidly succeed one another without intermission, then the body 

 collapses, bursts, and in the remaining (more or less homogeneous) 

 mass, no trace of the cage is left; as if the granules, not finding a 

 sufficiently wide way of egress, had all exploded inside the body. 



A second fact seems to argue for the same theory: the line of 

 the leap, the figure described in space by the displacement of the 

 body. It is always, as we said, an arc, or a circle when the com- 

 motion is particularly violent, and always — if I observed well — 

 with the same orientation. Now the pharyngeal pit is narrowed 

 in its anterior part into a tubular passage, somewhat curved towards 

 the ventral side, and on the supposition of a sudden emission of 

 matter through this aperture, the backward jumping must describe 

 a circular figure wdth the concave side of the body facing towards 

 the center. The very form of Cryptomonas might be supposed to 

 necessitate that particular direction, but, as we saw before, Cry-pto- 

 monas may present the most different forms, the smaller individuals 

 being even oval in shape, and yet the jumps never show any differ- 

 ence at all. 



But I must now point to a fact, which though appearing at first 

 not to be related to this subject, might on the contrary prove of 

 the greatest importance. At the end of January, 1917, in my col- 



